NES have different etiologies, and have been divided into “physiological NES” and “psychogenic NES,” also referred to as pseudoseizures in the past (5). We address the “psychogenic NES,” or the NES associated with psychological correlates, in this chapter. The differential diagnosis for NES includes those physiological events that may mimic epilepsy, but that are neither epileptic nor psychological in origin. These physiological NES include syncopal and anoxic events, parasomnias, movement disorders, migraines, and other miscellaneous neurological events (6) (Table 25.1).

Psychological disorders associated with NES can be divided into conversion/ dissociation NES, psychiatric disorders with seizure-like activity (e.g., panic attacks with shaking or catatonic states in depression), and factitious disorder (7). These NES-associated psychiatric disorders are described in the subsequent text.

Conversion disorders (CDs)—Symptoms in CDs are defined as, “a loss of, or alteration in, voluntary motor or sensory functioning suggesting a neurological or general medical condition. Psychological factors are judged to be associated with the development of the symptom, and the symptom is not fully explained by a neurological or general medical condition or the direct effects

of a substance” (8). CDs may occur in the presence of neurological disease, and the two are not mutually exclusive. The NES that are described as types of CDs or as dissociative phenomena, are usually considered the result of unconscious processes.

Dissociative states—Dissociation is both a mechanism and a disorder. It is characterized in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) definition as, “a disruption in the usual integrated functions of consciousness, memory, identity, or perception of environment” (8). Dissociation occurs in a variety of neurological and psychiatric disorders, ranging from temporal lobe epilepsy (TLE), to post-traumatic stress disorder (PTSD), to dissociative disorders, to NES (9,10). Some dissociative episodes are therefore due to ictal manifestations of abnormal neuronal behavior, and others due to anxiety-based defense responses to physical and psychological trauma (11). The World Health Organization (WHO) diagnostic categorization of dissociation suggests a mechanistic relationship to psychological etiology, related to “trauma, insoluble or intolerable problems, or disturbed relationships” (12). Along with acute and chronic posttraumatic disorders, dissociation occurs in affective disorders and in certain personality disorders. Dissociation in NES may lead to the misdiagnosis of epilepsy, with the reporting of amnesia and with abnormal EEG found in some patients having dissociative episodes (13). Other dissociative symptoms include depersonalization and derealization, referring to a disturbance of feeling about the self or the surrounding world, respectively. Autoscopy refers to the out-of-body experiences where an individual reports standing outside his or her body and looks down on it. Déjà vu and jamais vu represent amnestic dislocations, with déjà vu most commonly occurring in anxiety disorder. The dissociative symptoms of the TLE aura are more vivid and often repetitive in a more stereotyped manner than those of the psychologically driven variety (14).

Panic attacks present as paroxysmal episodes with autonomic symptomatology, including a combination of tachycardia, palpitations, hyperventilation, dyspnea, diaphoresis, angina, tremulousness, presyncope, visual changes, and “an impending sense of doom.” They may occur in stressful situations or even sporadically, once they have become dissociated from the feared stimulus. Differentiating seizures with panic from pure anxiety, with the considerable semiological overlap between ictal fear and panic symptoms, can be difficult. Panic that is consistently sporadic and nonsituational is more apt to be ictal in origin. Also, the diffuse symptoms of anxiety differ from the “dreamy state” and automatisms described by Hughlings-Jackson (15) and the epigastric rising sensation reported in TLE before loss of consciousness, and personality measures of anxiety are higher in patients with NES than in patients with epilepsy (16).

As is the case with dissociation, alterations in consciousness are found in catatonic states and may be associated with cerebral dysfunction, toxic metabolic states, or due to psychogenic causes. Among the psychiatric diagnoses, catatonia is often associated with schizophrenia; however, catatonia occurs in severe affective disorders also. Catatonia is a disturbance of motor behavior with psychological or neurological etiologies, which manifests as rigid immobility for extended periods, or as agitated purposeless motor activity (8).

Episodic dyscontrol is a condition of repeated paroxysmal episodes of rage and violence, which often occur sporadically without a precipitant, and are relatively short lived (17). Similarly, individuals diagnosed with “intermittent explosive disorder (IED),” may be amnestic of the events that result in serious assaults toward people or property destruction (8). Episodic dyscontrol and IED are found in boys, in urban areas, often with a family history of violence (17). IED may be confused with epilepsy, with the transient change in consciousness, the response to antiepileptic/mood stabilizing drugs, some association with a history of head injury, and an abnormal EEG with nonspecific slowing in a third of patients in one series (18,19).

Factitious disorders occur in patients who intentionally produce physical or psychological symptoms to assume the sick role, who do not have external incentives for producing the behavior (20). Patients may manifest a history of prior ES, and may feign a convulsion, or may have dissociative experiences resembling complex partial or absence seizures (21). Munchausen by proxy is the production of symptoms in another individual, often involving a child and its mother, and factitious epilepsy has been documented in children and adults (22).

In contrast to the psychiatric disorders mentioned in the preceding text, malingering, which makes up a small subset of patients with NES and is not considered as a psychiatric illness, is instead thought of as a conscious process of deception. Malingering using epileptic-like symptoms has been documented in the medical literature for over a century (23,24). The DSM-IV categorizes malingering under “additional conditions that may be a focus of clinical attention,” defining it as the intentional production of false or exaggerated symptoms, motivated by external incentives (8). Malingering may occur under the threat of imminent undesirable circumstances, such as military service, jail, work, or a difficult social situation, but it is most often discovered in the setting of obtaining illicit drugs or compensation.

The differential diagnosis of physiological and psychological NES informs the respective treatments of patients with NES (25), and current treatment approaches are addressed at length in Chapter 27.

Of the 1% of the US population diagnosed with epilepsy, 5% to 20% have NES (26). It is estimated that 10% of those with NES have mixed ES/NES (27), and estimates for the coexistence of ES and NES vary from less than 10% to more than 40% (28). The incidence of NES has been estimated to be 3.03 per 100,000 (29), and the prevalence of NES is estimated to be up to 33 per 100,000 (30). Patients with NES are usually women (∼80%) and are between 15 and 35 years old (∼80%) (31), although children and the elderly can develop NES (32,33,34). A history of recent or past physical or emotional trauma and/or prior abuse is occasionally, if not frequently, encountered in patients with NES, according to some observers (35). There is often significant neurological comorbidity in patients with NES. For example, in a study of 45 consecutive patients with NES, Kanner et al. found a history of epilepsy in 42%, and abnormal findings on brain magnetic resonance imaging (MRI) studies in 40%, including 33% with a structural lesion (36). The full array of risk factors and their relative import for the development of NES has not been defined, stringently.

The diagnosis of NES carries significant implications for prognosis and attendant morbidity. It has been estimated that up to 14% of patients with NES may be transferred to an intensive care unit from the emergency department in unrecognized pseudostatus epilepticus, as one manifestation of NES (37). With respect to outcomes, Reuber et al. found that 71% of patients with NES continued to have episodes and half the number of patients remained on disability in longitudinal follow-up (37). Prognostic indicators for remission of NES include having a shorter duration of NES from symptom onset to diagnosis (<1 year), and having “catatonic” type spells, as compared with “thrashing” spells (38). Kanner found that NES persisted in patients who had a combination of affective disorder, personality disorder, and a history of chronic abuse (36).

A number of instruments are used to assist in the diagnosis of NES. After conducting a thorough history, and mental status and neurological examination, clinicians may utilize neurophysiological, neurohumoral, and neuropsychological (NP) tests to assist in the diagnosis of NES.